Apparatus for Treating Wafers Using Supercritical Fluid

ABSTRACT

Provided are an apparatus and method for treating wafers using a supercritical fluid. The wafer treatment apparatus includes a plurality of chambers; a first supply supplying a first fluid in a supercritical state; a second supply supplying a mixture of the first fluid and a second fluid; a plurality of first and second valves; and a controller selecting a first chamber of the plurality of chambers for wafer treatment to control the open/closed state of each of the plurality of first valves so that the first fluid can be supplied only to the first chamber of the plurality of chambers and selecting a second chamber of the plurality of chambers to control the open/closed state of each of the plurality of second valves so that the mixture of the first fluid and a second fluid can be supplied only to the second chamber of the plurality of chambers. The wafer treatment method involves performing a predetermined treatment such as etching, cleaning or drying on wafers within only one of the plurality of chambers, followed by wafer treatment on the succeeding chamber, and thus allowing for sequential wafer treatment within each of the plurality of chambers.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of Korean Patent Application No.10-2006-0074316, filed on Aug. 7, 2006, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

FIELD OF THE INVENTION

The present invention relates generally to semiconductor devices and,more particularly, to apparatus and methods for fabricatingsemiconductor devices.

BACKGROUND OF INVENTION

As the design rules of semiconductor devices change, it has becomeincreasingly necessary to form deeper, narrower contacts with higheraspect ratios. The formation of a deep, narrow contact with a highaspect ratio involves an etching or cleaning step. When treating a waferon which a high aspect ratio structure is formed by etching, cleaning,or drying the wafer, defects may frequently occur due to damage to otherlayers of the wafer and/or water spots on a wafer surface when aconventional wet etching process is utilized. Furthermore, when a wetetching process is performed to remove a mold oxide layer, which is usedas a sacrificial layer when forming a storage node for a capacitor, thestorage node of the capacitor tends to lean or collapse after theremoval of the mold oxide layer due to the high surface tension of purewater.

To solve the above-mentioned problems, etching, cleaning, and/or dryinga predetermined layer on a wafer using a supercritical CO₂ solvent havebeen proposed. Unfortunately, conventional methods for treating wafersusing supercritical CO₂ solvent may allow only one wafer to be treatedat a time in order to maintain a high temperature, a high pressuresupercritical state. As such, the use of supercritical CO₂ processingmay cause reduced process throughput.

SUMMARY OF THE INVENTION

The present invention provides apparatus for treating wafers using asupercritical fluid that can offer improved uniformity between wafers aswell as improved process throughput by reducing unnecessary loss of timewhen a large number of wafers are treated.

The present invention also provides methods of treating wafers using asupercritical fluid that can offer improved uniformity between wafers aswell as improved process throughput by reducing unnecessary loss of timewhen a large number of wafers are treated.

According to an embodiment of the present invention, there is provided awafer treatment apparatus including: a wafer treating unit including aplurality of chambers; a fluid supply unit including a first supply thatsupplies a first fluid in a supercritical state to the wafer treatingunit and a second supply that supplies a mixture of the first fluid anda second fluid to the wafer treating unit; a plurality of first supplylines, each of which is connected between the first supply and one ofthe plurality of chambers and feeds the first fluid supplied from thefirst supply into the plurality of chambers; a plurality of secondsupply lines, each of which is connected between the second supply andone of the plurality of chambers and supplies the mixture supplied fromthe second supply to the plurality of chambers; a plurality of firstvalves that are disposed on the corresponding plurality of first supplylines and allows or blocks the supply of the first fluid through theplurality of first supply lines; a plurality of second valves that aredisposed on the corresponding plurality of second supply lines andallows or blocks the supply of the mixture supplied from the secondsupply through the plurality of second supply lines; and a controllerthat selects a first chamber of the plurality of chambers for wafertreatment in order to control the open/closed state of each of theplurality of first valves so that the first fluid can be supplied onlyto the first chamber of the plurality of chambers and that selects asecond chamber of the plurality of chambers in order to control theopen/closed state of each of the plurality of second valves so that themixture supplied from the second supply can be supplied only to thesecond chamber of the plurality of chambers.

The first fluid may be composed of super- critical CO₂. The second fluidmay be composed of an alcohol-based cosolvent, fluorine-containingcompound, or a mixture thereof.

The wafer treatment apparatus may further include a plurality of timersthat are disposed near the corresponding plurality of chambers andcontrol the time for wafer treatment within the chambers.

The apparatus may further include a plurality of pressure adjustingelements that are disposed near the corresponding plurality of chambersand control the pressure within the chambers and the pressure in thefirst and second supply lines.

Each of the plurality of chambers includes a pair of cases mutuallyfitted to open and close in order to define a treatment space fortreating wafers and a plurality of chucks that are fixed to the pair ofcases that support the wafers within the treatment space.

The first supply may include a first bombe supplying the first fluid ina liquid state at a first pressure and a condenser compressing the firstfluid supplied from the first bombe at a second pressure higher than thefirst pressure to create a supercritical fluid. The first supply mayfurther include a booster pump that is disposed between the condenserand the wafer treating unit and that increases the pressure of the firstfluid escaping from the condenser.

The apparatus may further include a separator separating a supercriticalfluid from a fluid escaping from each of the chambers in the wafertreating unit and a recycle filter filtering out the supercritical fluidobtained by the separator and feeding the supercritical fluid back tothe first supply.

The controller can control the open/closed state of the plurality offirst and second valves so as to enable simultaneous supply of the firstfluid and the mixture supplied from the second supply to the first andsecond chambers of the plurality of chambers, respectively.

According to another embodiment of the present invention, there isprovided a wafer treatment method including operations of: preparing aplurality of chambers connected to first supply lines that supply afirst fluid in a supercritical state and second supply lines that supplya mixture of the first fluid and a second fluid; loading a pair ofwafers into a first chamber of the plurality of chambers so that thepair of wafers are spaced apart by a predetermined distancecorresponding to a treatment space, with the front sides of the pair ofwafers facing each other; performing a first pretreatment on the pair ofwafers by supplying the first fluid fed through the first supply line tothe treatment space within the first chamber; performing a firsttreatment on the pair of wafers by supplying the mixture fed through thesecond supply line to the treatment space within the first chamber; andunloading the wafers from the first chamber of the plurality ofchambers.

The wafer treatment method may further include operations of: loadingthe pair of wafers into a second chamber of the plurality of chambers sothat the pair of wafers are spaced apart by a predetermined distancecorresponding to the treatment space within the second chamber, with thefront sides of the pair of wafers facing each other; performing a secondwafer treatment on the pair of wafers within the second chamber of theplurality of chambers by supplying the mixture fed through the secondsupply line to the treatment space within the second chamber of theplurality of chambers simultaneously with the first unloading, followingthe first wafer treatment; and unloading the pair of wafers from thesecond chamber of the plurality of chambers.

The method may further include operations of: loading a pair of wafersinto a third chamber of the plurality of chambers so that the pair ofwafers are spaced apart by a predetermined distance corresponding to atreatment space within the third chamber, with the front sides of thepair of wafers facing each other; performing a third treatment on thewafers within the third chamber of the plurality of chambers bysupplying the mixture fed through the second supply line to thetreatment space within the third chamber simultaneously with the secondunloading, following the second wafer treatment; and unloading thewafers from the third chamber of the plurality of chambers.

The method may further include operations of: after unloading of thewafers from the first chamber, loading two wafers into the first chamberso that the two wafers are spaced apart by a predetermined distancecorresponding to a treatment space, with the front sides facing eachother, wherein the number of chambers is a natural number N greater thanor equal to 3; and when predetermined treatment is performed on waferswithin all of the N chambers, performing an N+1-st treatment on the twowafers within the first chamber, immediately following a predeterminedtreatment on wafers within an N-th chamber that is the last one of the Nchambers.

The method may further include the operation of, before performing theN+1st treatment, performing an N+1st pretreatment on the pair of wafersby supplying the first fluid fed through the first supply line to thetreatment space within the first chamber at the same time as thepredetermined treatment on the pair of wafers within the N-th chamber ofthe plurality of chambers. The wafer treatment method of the presentinvention also allows simultaneous treatment of at least two wafersloaded into a single chamber, thus increasing process throughput.

Thus, the present invention can reduce the amount of time required totreat a plurality of wafers using a supercritical fluid, thus increasingproductivity. The present invention also enables sequential wafertreatment within each of a plurality of chambers, thus improvinguniformity across treated wafers.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with the attached drawings in which:

FIG. 1 is a schematic diagram illustrating the main components of awafer treatment apparatus according to an embodiment of the presentinvention;

FIG. 2 illustrates the detailed configuration of a first supply of thewafer treatment apparatus illustrated in FIG. 1, according to anembodiment of the present invention;

FIG. 3 illustrates a second supply of the wafer treatment apparatusillustrated in FIG. 1 that supplies a second fluid, according to anembodiment of the present invention;

FIG. 4A is a perspective view illustrating a chamber of the wafertreatment apparatus illustrated FIG. 1, according to an embodiment ofthe present invention;

FIG. 4B is a longitudinally sectional view of the chamber of the wafertreatment apparatus illustrated in FIG. 4A, according to an embodimentof the present invention;

FIG. 5 is a flowchart illustrating a wafer treatment method according toan embodiment of the present invention;

FIG. 6 is a graph illustrating a pressure profile with respect to timewithin each of the chambers when the wafer treatment time is set to 1minute when performing a wafer treatment method according to anembodiment of the present invention;

FIG. 7 is a graph illustrating a pressure profile with respect to timewithin each of the chambers when the wafer treatment time is set to 3minutes when performing a wafer treatment method according to anotherembodiment of the present invention; and

FIG. 8 is a graph illustrating a pressure profile with respect to timewithin each of the chambers when the wafer treatment time is set to 5minutes when performing a wafer treatment method according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference tothe accompanying drawings, in which embodiments of the invention areshown.

The invention will be described more fully hereinafter with reference tothe accompanying drawings, in which example embodiments of the inventionare shown. This invention may, however, be embodied in many differentforms and should not be construed as limited to the example embodimentsset forth herein. Rather, the disclosed embodiments are provided so thatthis disclosure will be thorough and complete, and will fully convey thescope of the invention to those skilled in the art. In the drawings, thesize and relative sizes of layers and regions may be exaggerated forclarity. Moreover, each embodiment described and illustrated hereinincludes its complementary conductivity type embodiment as well. Likenumbers refer to like elements throughout.

It will be understood that when an element or layer is referred to asbeing “on”, “connected to” and/or “coupled to” another element or layer,it can be directly on, connected or coupled to the other element orlayer or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directlyconnected to” and/or “directly coupled to” another element or layer,there are no intervening elements or layers present. As used herein, theterm “and/or” may include any and all combinations of one or more of theassociated listed items.

It will be understood that, although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsmay be used to distinguish one element, component, region; layer and/orsection from another region, layer and/or section. For example, a firstelement, component, region, layer and/or section discussed below couldbe termed a second element, component, region, layer and/or sectionwithout departing from the teachings of the present invention.

Spatially relative terms, such as “below”, “lower”, “above”, “upper” andthe like, may be used herein for ease of description to describe anelement and/or a feature's relationship to another elements) and/orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90° or atother orientations) and the spatially relative descriptors used hereininterpreted accordingly. Moreover, the term “beneath” indicates arelationship of one layer or region to another layer or region relativeto the substrate, as illustrated in the figures.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular terms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes” and/or “including” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Example embodiments of the invention are described herein with referenceto plan and cross-section illustrations that are schematic illustrationsof idealized embodiments (and intermediate structures) of the invention.As such, variations from the shapes of the illustrations as a result,for example, of manufacturing techniques and/or tolerances, may beexpected. Thus, the disclosed example embodiments of the inventionshould not be construed as limited to the particular shapes of regionsillustrated herein unless expressly so defined herein, but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe invention, unless expressly so defined herein.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

FIG. 1 is a schematic diagram illustrating the main components of awafer treatment apparatus according to an embodiment of the presentinvention.

Referring to FIG. 1, the wafer treating apparatus includes a wafertreating unit 100 having a plurality of chambers 120 C₁ through C_(N) (Nis a natural number) and a fluid supply unit 200 that supplies fluids,which are required for performing a predetermined treatment such asetching, cleaning or drying on a wafer, to each of the chambers 120 C₁through C_(N). The fluid supply unit 200 includes a first supply 210that supplies a first fluid 212 in a supercritical state to the wafertreating unit 100 and a second supply 220 that supplies a mixture of thefirst fluid 212 and a second fluid 214 to the wafer treating unit 100.The second supply 220 includes a mixing tank 224 that mixes the firstfluid 212 with the second fluid 214.

The first fluid 212 may be composed of, for example, supercritical CO₂.The second fluid 214 may be composed of, for example, an alcohol-basedcosolvent, a fluorine-containing compound, or a mixture thereof.

A process that involves etching a predetermined layer on a wafer may beperformed within each of the chambers 120 C₁ through C_(N) in the wafertreating unit 100. According to embodiments of the present invention,when the predetermined layer is an oxide layer, the second fluid 214 maycontain a mixture of fluorine-containing compound and pyridine.Alternatively, the second fluid 214 may contain at least one materialselected from the group consisting of sodium bis(2,2,3,3,4,4,5,5-octafluoro-1-pentyl)-2-sulfosuccinate (F-AOT), fluorine-basedsurfactant, and alcohol-based cosolvent. For example, the alcohol-basedcosolvent may be methanol, ethanol, isopropyl alcohol (IPA), orpropanol.

The process performed within each of the chambers 120 C₁ through C_(N)may include the operation of etching a predetermined layer on a waferand a cleaning step for removing a product remaining on a wafer afterthe etching step. The process may only include the operation of cleaninga wafer surface. According to embodiments of the present invention, thecleaning step may be performed using a mixture of the first fluid 212composed of supercritical CO₂ and the second fluid 214, which iscomposed of a cosolvent.

Materials contained in the first and second fluid 214 may vary dependingon the type of a layer on a wafer that is to be etched or cleaned.

The illustrated wafer treatment apparatus further includes a pluralityof first supply lines 230, each of which is disposed between the firstsupply 210 and one of the plurality of chambers 120 C₁ through C_(N) andfeeds the first fluid 212 supplied from the first supply 210 into theplurality of chambers 120 C₁ through C_(N).

The first fluid 212 that is supplied from the first supply 210 can befed into the plurality of chambers 120 C₁ through C_(N) through a firstbranch line 216 and the plurality of supply lines 230. The supply of thefirst fluid 212 to the plurality of chambers 120 C₁ through C_(N) may beallowed or blocked by opening or closing a plurality of first valves 232corresponding to the plurality of first supply lines 230, asillustrated.

The first fluid 212 is supplied from the first supply 210 to the mixingtank 224 through a second branch line 218. The mixing tank 224 mixes thefirst fluid 212 supplied from the first supply 210 with the second fluid214 supplied through a supply line 226. The wafer treatment apparatusfurther includes a plurality of second supply lines 240, each of whichis disposed between the second supply 220 and one of the plurality ofchambers 120 C₁ through C_(N) and supplies a mixture of the first andsecond fluids 212 and 214 obtained from the mixing tank 224 to theplurality of chambers 120 C₁ through C_(N). The supply of the mixture ofthe first and second fluids 212 and 214 to the plurality of chambers 120C₁ through C_(N) may be allowed or blocked by opening or closing a checkvalve 242 installed on a supply line 244 and a plurality of secondvalves 234, each of which is installed on one of the plurality of firstsupply lines 240, as illustrated.

A treatment time controller 260 is disposed behind the wafer treatingunit 100 and includes a plurality of timers 262 that control the time ofwafer treatment within the plurality of chambers 120 C₁ through C_(N). Apressure adjusting unit 270 is disposed behind the plurality of chambers120 C₁ through C_(N) and includes a plurality of pressure regulators 272that control the pressure within the plurality of chambers 120 C₁through C_(N) and the pressure in a part of the wafer treatmentapparatus disposed in front of the wafer treating unit 100 and, inparticular, in the plurality of first and second supply lines 230 and240.

In order to perform a predetermined wafer treatment for a selected oneof the plurality of chambers 120 C₁ through C_(N) in the wafer treatingunit 100, a fluid may be allowed to flow only into the selected chamber120 of the plurality of chambers 120 C₁ through C_(N) by controlling theopen/closed state of each of the plurality of first and second valves232 and 234 and the check valve 242. A controller 250 may control theopen/closed state of each valve of the supply line valve unit 290including the plurality of first valves 232, the plurality of secondvalves 234, and the check valve 242. That is, the controller 250 cancontrol the open/closed state of each of the plurality of first andsecond valves 232 and 234 and the check valve 242 in the supply linevalve unit 290 so that the first fluid 212 or the mixture of the firstand second fluids 212 and 214 can be fed into the selected chamber 120of the plurality of chambers 120 C₁ through C_(N). Alternatively, thecontroller 250 can select a chamber 120 from the plurality of chambers120 C₁ through C_(N) other than the chamber 120 receiving the firstfluid 212 and control the open/closed state of each of the first andsecond valves 232 and 234 and the check valve 242 so that a mixture ofthe first and second fluids 212 and 214 can be supplied to the selectedchamber 120 of the plurality of chambers 120 C₁ through C_(N).

The controller 250 may also control the open/closed state of each of theplurality of first and second valves 232 and 234 and the check valve 242in the supply line valve unit 290 so that the first fluid 212 is fedinto one of the plurality of chambers 120 C₁ through C_(N) at the sametime that a mixture of the first and second fluids 212 and 214 issupplied to another one of the plurality of chambers 120 C₁ throughC_(N).

The controller 250 also delivers a predetermined control signal to thewafer treating unit 100 and a loadlock 110 that is near the wafertreating unit 100 to control the carriage of wafers between a selectedchamber 120 of the plurality of chambers 120 C₁ through C_(N) and theloadlock 110, i.e., loading/unloading of a wafer into/from the selectedchamber 120 of the plurality of chambers 120 C₁ through C_(N). In thiscase, wafer treatment can be performed within only the selected chamber120 of the plurality of chambers 120 C₁ through C_(N). The controller250 may control the open/closed state of each valve in the supply linevalve unit 290 and the loading/unloading of wafers into/from each of theplurality of chambers 120 C₁ through C_(N) so that all of the pluralityof chambers 120 C₁ through C_(N) can be sequentially used for wafertreatment by sequentially performing wafer treatment in each of theplurality of chambers 120 C₁ through C_(N) until the desired treatmentis performed on all the wafers.

After completing the predetermined wafer treatment within the selectedchamber 120 of the plurality of chambers 120 C₁ through C_(N) in thewafer treating unit 100, a residual fluid in the chambers 120 isdischarged into a separator 280 via an exhaust line 282 disposed at thedownstream of the wafer treating unit 100. A check valve 284 isinstalled on the exhaust line 282 and controls the flow of fluid throughthe exhaust line 282.

The separator 280 acts to neutralize a fluid discharged from each of theplurality of chambers 120 C₁ through C_(N) in the wafer treating unit100. For example, when hydrogen fluoride (HF) escapes from the chambers120, a 1M aqueous NaOH solution may be accommodated within the separator280 to neutralize the acidity. That is, if an acid fluid escapes fromthe plurality of chambers 120 C₁ through C_(N), an alkaline solution isprovided within the separator 280. Conversely, if an alkaline fluidescapes from the plurality of chambers 120 C₁ through C_(N), an acidsolution is provided within the separator 280.

The separator 280 also separates a supercritical fluid such assupercritical CO₂ from a fluid discharged from each of the plurality ofchambers 120 C₁ through C_(N), receives the supercritical fluid througha supercritical fluid recycle filter 288, and feeds the receivedsupercritical fluid back into a bombe (not shown) in the first supply210 holding the material of the supercritical fluid.

The supply line valve unit 290 may further include a booster pump (notshown) that increases the pressure of a fluid being supplied through thefirst branch line 216 or the supply line 244 corresponding to thepressure that can be actually applied in the wafer treating unit 100before the fluid reaches the wafer treating unit 100.

FIG. 2 illustrates the detailed configuration of the first supply 210 ofthe wafer treatment apparatus illustrated in FIG. 1, according to anembodiment of the present invention.

Referring to FIG. 2, the first supply 210 of the wafer treatmentapparatus includes a bombe 20 containing the material of the first fluid212 such as CO₂. The CO₂ stored in the bombe 20 is supplied to acondenser 22 as a liquid at a pressure of about 800 psi. The condenser22 compresses the material supplied from the bombe 20 at a higherpressure than 800 psi to create a supercritical fluid. The supercriticalfluid that escapes from the condenser 22 becomes the first fluid 212 ina supercritical state having a higher pressure of about 2,000 to 3,500psi as it passes through a booster pump 24. The first fluid 212 istransferred to the first or second branch line 216 or 218 according tothe opening/closing operations of valves 26, 32, and 34 respectivelymounted on a supply line 28 disposed behind the booster pump 24 and thefirst and second branch lines 216 and 218.

Although not shown, the first supply 210 may further include a coolingjacket and a temperature regulating cooler installed between the bombe20 and the condenser 22. The cooling jacket maintains the temperature ofthe material of the supercritical fluid supplied from the bombe 20 at adesired level. The temperature regulating cooler controls thetemperatures of materials set within the cooling jacket and thecondenser 22. The first supply 210 may further include a heating band(not shown) that covers a fluid flowing through the second branch line218 and the supply lines 226 and 244 to maintain the temperature of thefluid flowing through the second branch line 218 and the supply lines226 and 244 at an appropriate level, e.g., within a range of about 40 to60° C.

FIG. 3 illustrates the second supply 220 of the wafer treatmentapparatus illustrated in FIG. 1 that supplies the second fluid 214,according to an embodiment of the present invention;

Referring to FIG. 3, the second supply 220 of the wafer treatmentapparatus includes a plurality of bombes 42, 44, and 46 supplyingvarious kinds of medicines or solvents required to etch a predeterminedlayer on a wafer or clean a wafer surface. For example, each of theplurality of bombes 42, 44, and 46 may hold a fluorine-containingcompound, surfactant, or alcohol-based solvent. The materials suppliedfrom the plurality of the bombes 42, 44, and 46 can be selectively fedinto one of the plurality of chambers 120 C₁ through C_(N) via thesupply line 226 according to the opening/closing operation of valves 52,54, and 56. A booster pump 60 is mounted on the supply line 226 andincreases the pressure of the materials received from the plurality ofbombes 42, 44, and 46. A check valve 62 is installed on the supply line226 and controls the operation of transferring the materials receivedfrom the plurality of bombes 42, 44, 46 into the wafer treating unit 100according to an opening/closing operation of the check valve 62.

FIG. 4A is a perspective view illustrating one of the plurality ofchambers 120 C₁ through C_(N) of the wafer treatment apparatusillustrated in FIG. 1 and FIG. 4B is a longitudinally sectional view ofone of the plurality of chambers 120 C₁ through C_(N) of the wafertreatment apparatus illustrated FIG. 4A, according to an embodiment ofthe present invention.

Referring to FIGS. 4A and 4B, the plurality of chambers 120 C₁ throughC_(N) in the wafer treatment apparatus include a pair of cases 122 and124 mutually fitted to open and close in order to define a treatmentspace S for treating wafers W₁ and W₂. The pair of cases 122 and 124 maybe formed of an anti-corrosive material such as, for example, hastelloyor monel metal. The height H of the sealed chamber 120 defined by thepair of cases 122 and 124 that mutually fit with each other may be in arange of about 60 and 80 mm. The width W of the pair of cases 122 and124 may be in a range of about 300 and 400 mm. The plurality of chambers120 C₁ through C_(N) further include a housing 142 that encapsulates thepair of cases 122 and 124 so as to achieve firm sealing when the pair ofcases 122 and 124 mutually fit with each other to close the plurality ofchambers 120 C₁ through C_(N).

Each of the plurality of chambers 120 C₁ through C_(N) further includesa plurality of chucks 132 that are fixed to the pair of cases 122 and124 and hold the pair of wafers W₁ and W₂ within the treatment space S.FIG. 4B illustrates that each of the plurality of chambers 120 C₁through C_(N) includes a pair of chucks 132, each of which is fixed toone of the pair of cases 122 and 124, supporting both wafers W₁ and W₂so as to face each other. However, three or more wafers can be loadedinto the plurality of chambers 120 C₁ through C_(N) and each of theplurality of chambers 120 C₁ through C_(N) may have a number of chucks132 corresponding to the number of wafers being loaded into theplurality of chambers 120 C₁ through C_(N). The chucks 132 may befixedly mounted or rotatably mounted on the pair of cases 122 and 124.

Both wafers W₁ and W₂ may each be held by the chucks 132 in such amanner that the front sides M₁ and M₂ of the wafers are in face-to-facespaced apart relationships, as illustrated. For example, both 300-mmwafers W₁ and W₂ may be held by the chucks 132 within the plurality ofchambers 120 C₁ through C_(N) so that both 300-mm wafers W₁ and W₂ aresubjected to a predetermined treatment with the front sides of both300-mm wafers W₁ and W₂ facing each other.

The first fluid 212 or a mixture of the first and second fluids 212 and214 is introduced into the treatment space S through a fluid inlet port152 and escapes through a fluid outlet port 154. That is, the fluidflows along a direction parallel to a direction that the main surfacesof both the wafers W₁ and W₂ extend, as illustrated in FIG. 4B. In thepresent embodiment, a predetermined treatment is performed on the frontsides M₁ and M₂ of the wafers W₁ and W₂ using the first fluid 212 or themixture of the first and second fluids 212 and 214.

When the plurality of chambers 120 C₁ through C_(N) are installed in thewafer treating unit 100, both wafers W₁ and W₂ are horizontally loadedinto the plurality of chambers 120 C₁ through C_(N) as illustrated inFIG. 4B. Alternatively, both wafers W₁ and W₂ may be perpendicularlyloaded into the plurality of chambers 120 C₁ through C_(N), which isopposite to the direction illustrated in FIG. 4B.

In the wafer treatment apparatus according to an embodiment describedabove with reference to FIGS. 1, 2, 3, 4A, and 4B, a plurality ofwafers, e.g., both wafers W₁ and W₂, are loaded into each of theplurality of chambers 120 C₁ through C_(N). A supercritical fluid suchas pure supercritical CO₂ of about 1,000 to 3,500 psi is then injectedinto the plurality of chambers 120 C₁ through C_(N) into which wafers W₁and W₂ have been loaded. When the pressure within the plurality ofchambers 120 C₁ through C_(N) reaches a process pressure required forwafer treatment, the supercritical CO₂ flows through and escapes throughthe treatment space S within the plurality of chambers 120 C₁ throughC_(N). The pressure within the plurality of chambers 120 C₁ throughC_(N) is constantly maintained by the pressure regulators 272.

The wafer treatment begins by injecting a wafer treatment fluid, e.g., amixture of supercritical CO₂ for etching or cleaning and cosolvent onlyinto a first chamber C₁ of the plurality of chambers 120 C₁ throughC_(N). In this case, when the chucks 132 are spin chucks, the wafertreatment may be performed by rotating a wafer by the chucks 132 at apredetermined spin rate of 1 about to 2,000 rpm.

Once the wafer treatment is performed within the first chamber C₁ of theplurality of chambers 120 C₁ through C_(N), the flow of the fluid intothe first chamber C₁ of the plurality of chambers 120 C₁ through C_(N)is blocked and the pressure of supercritical CO₂ is reduced bydischarging the supercritical CO₂. Thereafter, both wafers W₁ and W₂ areunloaded from the first chamber C₁ of the plurality of chambers 120 C₁through C_(N).

After completing the wafer treatment within the first chamber C₁ of theplurality of chambers 120 C₁ through C_(N), a wafer treatment begins byinjecting a wafer treatment fluid, e.g., a mixture of supercritical CO₂for etching or cleaning and cosolvent only into a second chamber C₂ ofthe plurality of chambers 120 C₁ through C_(N). Thereafter, the sametreatment as described above is sequentially performed within each ofthe remaining chambers of the plurality of chambers 120 C₁ throughC_(N), i.e., third to N-th chambers C₃ through C_(N) of the plurality ofchambers 120 C₁ through C_(N), until the desired treatment is performedon all the wafers. After performing wafer treatment within the N-thchamber C_(N) of the plurality of chambers 120 C₁ through C_(N), thesame process as described above is repeated for the first through N-thchambers C₁ through C_(N) until a desired treatment is performed on allwafers to be treated therein.

FIG. 5 is a flowchart illustrating a wafer treatment method according toan embodiment of the present invention. However, it will be apparentthat various changes and modifications may be made to operationsillustrated in FIG. 5 without departing from the spirit and scope of thepresent invention. In operation 502, the plurality of chambers 120 C₁through C_(N) that are connected to the plurality of first and secondsupply lines 230 and 240 for supplying the first fluid 212 in asupercritical state and a mixture of the first fluid 212 and secondfluid 214 are prepared.

In operation 504, M is set to 0. In operation 506, M+1 is set to M. Inoperation 508, whether M=N is checked. If M=N, operation 530 isperformed. If not, operation 510 is performed.

In operation 510, both wafers W₁ and W₂ are loaded into each of M− andM+1-st chambers C_(M) and C_(M+1) so that both wafers W₁ and W₂ arespaced apart by a predetermined distance. That is, a predeterminedtreatment space is formed between both wafers W₁ and W₂ within thechamber M− or M+1-st chambers C_(M) or C_(M+1). Both wafers W₁ and W₂may be disposed with the front sides of both wafers W₁ and W₂ facingeach other.

In operation 512, both wafers W₁ and W₂ may be pretreated within the M−and M+1-st chambers C_(M) and C_(M+1). For pre-treatment, only the firstfluid 212 that is composed of supercritical CO₂ can be supplied to theM− and M+1-st chambers C_(M) and C_(M+1) through the first supply line230. By performing the pre-treatment, the atmosphere within the M− andM+1st chambers C_(M) and C_(m+1) can be preset close to a wafertreatment atmosphere. The pretreatment operation 512 may be omitted ifoperation 512 is not essential to the entire process.

Thereafter, when M=1 in operation 514, operation 516 is performed.Otherwise, operation 534 is performed.

In operation 516, the desired treatment is performed on both wafers W₁and W₂ loaded into the M-th chamber C_(M). For example, a mixture of thefirst fluid 212 composed of supercritical CO₂ for etching or cleaningand the second fluid 214 composed of a cosolvent can be supplied to theM-th chamber C_(M) through the second supply line 240 during thetreatment. A treatment atmosphere within the M-th chamber C_(M) can bemaintained at a temperature of about 30 to 100° C. and a pressure ofabout 1,000 to 4,500 psi. Furthermore, both wafers W₁ and W₂ can berotated at a spin rate of about 1 to 2,000 rpm as they are subjected tothe treatment. Fluids necessary for the wafer treatment flow into andout of the M-th chamber C_(M) at a flow rate of about 1 to 5,000 ml/minduring the wafer treatment. The density of co-solvent contained in themixture may be about 0.1 to 10 volume %, preferably, about 0.1 to 5volume % based on the total volume of supercritical CO₂. The processtime within the M-th chamber C_(M) may be adjusted by the timer 262.

After performing the wafer treatment in operation 516, both wafers W₁and W₂ are unloaded from the M-th chamber C_(M) in operation 518. Aftercompleting treatment within the M-th chamber C_(M), the desiredtreatment is successively performed on both wafers W₁ and W₂ that areloaded into the M+1-st chamber C_(M+1). Wafer unloading is performedwithin the M-th chamber C_(M) simultaneously with wafer treatment withinthe M+1-st chamber C_(M+1). The treatment is performed within the M+1stchamber C_(m+1) in the same manner as described in operation 516.

After completing the wafer treatment within the M+1st chamber C_(M+1),both wafers W₁ and W₂ are unloaded from the M+1st chamber C_(M+1). Then,the process returns to operation 506 to perform the same operations asdescribed above.

If M=N in operation 508, i.e., wafer treatment is performed on the lastone of the plurality of chambers 120 C₁ through C_(N), both wafers W₁and W₂ are loaded into the M-th chamber C_(N) and the first chamber C₁in operation 530.

In operation 532, a pretreatment is subsequently performed on the waferswithin the M-th chamber C_(N) and the first chamber C₁. The pretreatmentcan be performed in the same manner as described in operation 512 duringor before wafer treatment on an M−1st chamber C_(m−1) preceding the M-thchamber C_(N).

In operation 534, after completing the wafer treatment within the M−1stchamber C_(m−1), both wafers W₁ and W₂ are unloaded from the M−1stchamber C_(m−1) at the same time as wafer treatment within the M-thchamber C_(N). The wafer treatment is performed within the M-th chamberC_(N) in the same manner as described in operation 516.

After completing the wafer treatment within the M-th chamber C_(N), bothwafers W₁ and W₂ are unloaded from the M-th chamber C_(N). In this case,when the M-th chamber C_(N) is the last one of the plurality of chambers120 C₁ through C_(N), the wafer treatment is performed within the firstchamber C₁ at the same time as unloading of both wafers W₁ and W₂ fromthe M-th chamber C_(N) in operation 538. The wafer treatment can beperformed within the first chamber C₁ in the same way as described inoperation 516.

In operation 540, both wafers W₁ and W₂ are subsequently unloaded fromthe first chamber C₁. After performing operation 534, when the M-thchamber C_(N) is not the last one of the plurality of chambers 120 C₁through C_(N) in operation 536, the process returns to operation 518 inwhich wafer unloading is performed within the M-th chamber C_(m)simultaneously with wafer treatment within the M+1st chamber C_(m+1).

When there are remaining wafers to be treated, M is set to 0 inoperation 544 and operations 506 through 542 are repeated. Once thedesired wafer treatment has been performed on all the wafers that are tobe treated, the wafer treatment process is terminated.

FIG. 6 is a graph illustrating a pressure profile with respect to timewithin each of the five chambers I through V of the plurality ofchambers 120 C₁ through C_(N) when a wafer is treated for 1 minute usinga wafer treatment apparatus including the five chambers I through V ofthe plurality of chambers 120 C₁ through C_(N) according to the presentinvention. The graph is intended to explain a wafer treatment methodaccording to an embodiment of the present invention.

FIGS. 7 and 8 are graphs respectively illustrating a pressure profilewith respect to time within each of three chambers I through III of theplurality of chambers 120 C₁ through C_(N) when a wafer is treated for 3and 5 minutes using a wafer treatment apparatus including the threechambers I through III of the plurality of chambers 120 C₁ through C_(N)in order to explain the wafer treatment method, according to anotherembodiments of the present invention.

The wafer treatments in operations 516, 518, 534, and 538 as illustratedin FIG. 5 corresponds to the time during which a predetermined pressureis maintained, i.e., portions indicated by oblique lines. In order tocreate an atmosphere for wafer treatment such as etching, cleaning, ordrying after wafers are loaded into a chamber of the plurality ofchambers 120 C₁ through C_(N) before wafer treatment on each wafer ofthe plurality of chambers 120 C₁ through C_(N), pressure boost time isrequired to increase the pressure within the chamber of the plurality ofchambers 120 C₁ through C_(N). The pressure boost time may include thetime for pretreatment performed on a wafer in operations 512 and 532 ofFIG. 5. Furthermore, after completing a predetermined treatment onwafers loaded into a chamber of the plurality of chambers 120 C₁ throughC_(N), pressure reduction time is required to reduce the pressure withinthe chamber for unloading of the wafers from the chamber.

The pressure boost time and pressure reduction time required before andafter the wafer treatment processes in FIGS. 6-8 are set to 2 minutes,respectively.

FIGS. 5 through 8 show that a predetermined treatment such as etching,cleaning or drying is performed on wafers within only one of theplurality of chambers 120 C₁ through C_(N), followed by wafer treatmenton the succeeding chamber. That is, wafer treatment is sequentiallyperformed within each of the plurality of chambers 120 C₁ through C_(N).Thus, additional time for pressure boost or reduction is not neededuntil wafer treatment is performed on all wafers within the plurality ofchambers 120 C₁ through C_(N). That is, the process time includes onlytime required for one pressure boost performed before treatment on thefirst wafer and time required for one pressure reduction after treatmenton the last wafer. Thus, a wafer treatment method according to thepresent invention can reduce the amount of time required to treat aplurality of wafers as compared to a wafer treatment method using asingle-wafer chamber.

As described above, a wafer treatment apparatus according to the presentinvention includes a plurality of chucks within a plurality of chambersto enable simultaneous treatment of a plurality of wafers. The wafertreatment apparatus also includes a controller for controlling theloading/unloading of wafers in the wafer treating unit as well as theopen/closed state of valves installed on fluid supply lines connected toeach of the plurality of chambers. A wafer treatment method according tothe present invention that can be performed using the wafer treatmentapparatus involves performing a predetermined treatment such as etching,cleaning or drying on wafers within only one of the plurality ofchambers, followed by wafer treatment on the succeeding chamber, andthus allowing for sequential wafer treatment within each of theplurality of chambers. Thus, the wafer treatment method of the presentinvention does not require additional time for pressure boost orreduction during a period of time when wafer treatment is performed onall wafers within the plurality of chambers. The wafer treatment methodof the present invention also allows simultaneous treatment of at leasttwo wafers loaded into a single chamber of the plurality of chambers,and thus increasing the process throughput. Thus, the present inventioncan reduce the amount of time required to treat a plurality of wafersusing a supercritical fluid, and thus increasing productivity. Thepresent invention also enables sequential wafer treatment within each ofthe plurality of chambers, and thus improving uniformity across treatedwafers.

In the drawings and specification, there have been disclosed embodimentsof the invention and, although specific terms are employed, they areused in a generic and descriptive sense only and not for purposes oflimitation, the scope of the invention being set forth in the followingclaims.

1-27. (canceled)
 28. A wafer treatment apparatus comprising: a wafertreating unit including a plurality of chambers; a fluid supply unitincluding a first supply that supplies a first fluid in a supercriticalstate to the wafer treating unit; a plurality of first supply lines,each of which is connected between the first supply and one of theplurality of chambers and feeds the first fluid from the first supplyinto the plurality of chambers; a plurality of first valves disposed onthe corresponding plurality of first supply lines that allow or blockflow of the first fluid through the plurality of first supply lines; anda controller configured to select a first chamber of the plurality ofchambers for wafer treatment in order to control the open/closed stateof each of the plurality of first valves so that the first fluid can besupplied only to the first chamber of the plurality of chambers, whereineach of the plurality of chambers comprises: a pair of cases mutuallyfitted to open and close in order to define a treatment space fortreating wafers; and a plurality of chucks that are fixed to the pair ofcases and support the wafers within the treatment space, the number ofthe plurality of chucks corresponding to the number of the wafers withinthe treatment space.
 29. The apparatus of claim 28, wherein the fluidsupply unit includes a second supply that supplies a mixture of thefirst fluid and a second fluid to the wafer treating unit; the apparatusfurther comprising a plurality of second supply lines, each of which isconnected between the second supply and one of the plurality of chambersand supplies the mixture from the second supply to the plurality ofchambers; and a plurality of second valves disposed on the correspondingplurality of second supply lines that allow or block flow of the mixturethrough the plurality of second supply lines.
 30. The apparatus of claim29, wherein the controller is further configured to select a secondchamber of the plurality of chambers in order to control the open/closedstate of each of the plurality of second valves so that the mixturesupplied from the second supply can be supplied only to the secondchamber of the plurality of chambers.
 31. The apparatus of claim 28,wherein the first fluid comprises super-critical CO₂.
 32. The apparatusof claim 29, wherein the first fluid comprises supercritical CO₂ and thesecond fluid comprises an alcohol-based cosolvent, fluorine-containingcompound, or a mixture thereof.
 33. The apparatus of claim 28, furthercomprising a plurality of timers that are disposed near thecorresponding plurality of chambers and that control the time for wafertreatment within the plurality of chambers.
 34. The apparatus of claim29, further comprising a plurality of pressure adjusting elements thatare disposed near the corresponding plurality of chambers and thatcontrol the pressure within the plurality of chambers and the pressurein the plurality of first and second supply lines.
 35. The apparatus ofclaim 28, wherein each of the plurality of chambers includes a pair ofchucks, each of which is fixed to one of the pair of cases, supporting apair of wafers so as to face each other.
 36. The apparatus of claim 28,wherein the pair of cases comprise hastelloy or monel metal.
 37. Theapparatus of claim 28, wherein the first supply comprises: a first bombethat supplies the first fluid in a liquid state at a first pressure; anda condenser that compresses the first fluid supplied from the firstbombe at a second pressure higher than the first pressure to create asupercritical fluid.
 38. The apparatus of claim 34, wherein the firstsupply further comprises a booster pump that is disposed between thecondenser and the wafer treating unit and that increases the pressure ofthe first fluid escaping from the condenser.
 39. The apparatus of claim28, further comprising: a separator that separates a supercritical fluidfrom a fluid escaping from each of the plurality of chambers in thewafer treating unit; and a recycle filter that filters out thesupercritical fluid obtained by the separator and that feeds thesupercritical, fluid back to the first supply.
 40. The apparatus ofclaim 30, wherein the controller controls the open/closed state of theplurality of first and second valves so as to enable simultaneous supplyof the first fluid and the mixture supplied from the second supply tothe first and second chambers of the plurality of chambers,respectively.
 41. A wafer treatment apparatus comprising: a wafertreating unit including a plurality of chambers; a fluid supply unitincluding a first supply that supplies a first fluid to the wafertreating unit and a second supply that supplies a second fluid to thewafer treating unit, the first and second fluid includes a fluid in asupercritical state; a plurality of first supply lines, each of which isconnected between the first supply and one of the plurality of chambersand feeds the first fluid from the first supply into the plurality ofchambers; a plurality of second supply lines, each of which is connectedbetween the second supply and one of the plurality of chambers andsupplies the second fluid from the second supply to the plurality ofchambers; a plurality of first valves disposed on the correspondingplurality of first supply lines that allow or block flow of the firstfluid through the plurality of first supply lines; a plurality of secondvalves disposed on the corresponding plurality of second supply linesthat allow or block flow of the second fluid through the plurality ofsecond supply lines; and a controller configured to select a firstchamber of the plurality of chambers for wafer treatment in order tocontrol the open/closed state of each of the plurality of first valvesso that the first fluid can be supplied only to the first chamber of theplurality of chambers and selecting a second chamber of the plurality ofchambers in order to control the open/closed state of each of theplurality of second valves so that the second fluid supplied from thesecond supply can be supplied only to the second chamber of theplurality of chambers, wherein each of the plurality of chamberscomprises a pair of cases and a plurality of chucks.
 42. The apparatusof claim 41, wherein the second fluid includes the fluid in asupercritical state and a fluid including an alcohol-based cosolvent,fluorine-containing compound, or a mixture thereof.
 43. The apparatus ofclaim 41, wherein the pair of cases is mutually fitted to open and closein order to define a treatment space for treating wafers, wherein theplurality of chucks are fixed to the pair of cases and are configured tosupport the wafers within the treatment space, and wherein the number ofthe plurality of chucks correspond to the number of the wafers withinthe treatment space.
 44. A wafer treatment apparatus comprising: a wafertreating unit including at least one chamber; a fluid supply unitincluding a first supply that supplies a first fluid in a supercriticalstate to the wafer treating unit; wherein each of the plurality ofchambers comprises a pair of cases and a plurality of chucks.
 45. Theapparatus of the claim 44, wherein the fluid supply unit furtherincludes a second supply of a mixture of the first fluid and a secondfluid.
 46. The apparatus of the claim 44, wherein the pair of cases aremutually fitted to open and close in order to define a treatment spacefor treating wafers.
 47. The apparatus of the claim 44, wherein theplurality of chucks are fixed to the pair of cases and are configured tosupport the wafers within the treatment space, and wherein the number ofthe plurality of chucks correspond to the number of the wafers withinthe treatment space.